Le 07/03/2024 à 11:08, Duncan Murdoch a écrit :
On 07/03/2024 4:16 a.m., Ivan Krylov wrote:
On Wed, 6 Mar 2024 13:46:55 -0500
Duncan Murdoch <murdoch.dun...@gmail.com> wrote:
is this just a more or less harmless error, thinking that
the dot needs escaping
I think it's this one. You are absolutely right that the dot doesn't
need escaping in either TRE (which is what's used inside exportPattern)
or PCRE. In PRCE, this regular expression would have worked as intended:
# We do match backslashes by mistake.
grepl('[\\.]', '\\')
# [1] TRUE
# In PCRE, this wouldn't have been a mistake.
grepl('[\\.]', c('\\', '.'), perl = TRUE)
# [1] FALSE TRUE
Thanks, I didn't realize that escaping in PCRE was optional.
Escaping is optional only in brackets []. Without them it becomes
mandatory if we want to catch just "." not any character :
grepl('.', c('\\', '.'), perl = TRUE)
#[1] TRUE TRUE
Best,
Serguei.
So the default exportPattern line could be
exportPattern("^[^.]")
and it would work even if things were changed so that PCRE was used
instead of TRE.
Duncan Murdoch
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